1. Go to the link: https://zh.wikiversity.org/w/index.php?title=Special:import (Require transwiki importer permission)
2. Filling the forms with settings below:

3. Click Import for about 2 minutes, the import failed and give the message below:

What happens if you retry the import? Do you get the same error or does it succeed now?

If I try again immediately it returns this message:

I've tried to import that article many times and it always fails. Importing other pages still works.

First, I can tell that the page and some revisions made it in. If we compare https://zh.wikipedia.org/w/index.php?title=%E9%82%AA%E5%85%B8%E9%9B%BB%E5%BD%B1%E5%88%97%E8%A1%A8&offset=&limit=250&action=history&uselang=en with https://zh.wikiversity.org/w/index.php?title=%E9%82%AA%E5%85%B8%E9%9B%BB%E5%BD%B1%E5%88%97%E8%A1%A8&offset=&limit=250&action=history&uselang=en the first 129 revisions were imported.

Checking the lengths of those revisions, 7 590 125 bytes made it in That doesn't seem too huge to be honest. All the revisions must have been dumped out to XML for the import to start properly, so we're not hitting a limit there.

The import was retried a few times and I can see batches of revisions got in, each batch in a single COMMIT and so from a single attempt to import:

• binlog db1075-bin.004013: first 82 revisions
• binlog db1075-bin.004020: next 26 revisions
• binlog db1075-bin.004022: next 21 revisions

From the first import attempt, at 5:34 UTC, we can see a couple InnoDB slow row locks: https://grafana.wikimedia.org/d/000000273/mysql?var-server=db1075&var-port=9104&var-dc=eqiad%20prometheus%2Fops&panelId=24&fullscreen&orgId=1&from=1559916497871&to=1560017834041
There's a logstash entry right around there that is probably connected somehow: https://logstash.wikimedia.org/goto/95152c63713c94a2429d5b4752ec528a

Here's a sample INSERT from the first batch that made it in so we can go back and look at it later (first revision in the batch):

INSERT /* MediaWiki\Revision\RevisionStore::insertRevisionRowOn  */  INTO `revision` (rev_page,rev_parent_id,rev_minor_edit,rev_timestamp,rev_deleted,rev_len,rev_sha1,rev_content_model,rev_content_format) VALUES ('13811','0','0','20170620065905','0','33434','of7pr8iky9ufr4cq5h546g70rkz87fu',NULL,NULL)

I wonder, if the import is tried again, whether more old revisions will show up.

I believe this is the same case as T219702: Page import can fail with "Lock wait timeout exceeded" in WikiPage::insertOn so maybe we can close as duplicate?

I don't know if it's exactly the same, because I didn't see other long (or short) running inserts around that time. I can copy/paste the relevant part of the binlog in a file if that's useful.

Found them (thanks, tendril)!
transaction: 78697996224, run time 14s, stamp 2019-06-08 05:37:38

INSERT /* WikiPage::insertOn */ IGNORE INTO `page` (page_namespace, page_title, page_restrictions, page_is_redirect, page_is_new, page_random, page_touched, page_latest, page_len) VALUES ('0', '??????', '', '0', '1', '0.163800399756', '20190608053733', '0', '0')

and
transaction 78697994684, run time 7s, stamp 2019-06-08 05:36:58

INSERT /* User::addToDatabase */ IGNORE INTO `user` (user_name, user_password, user_newpassword, user_email, user_email_authenticated, user_real_name, user_token, user_registration, user_editcount, user_touched) VALUES ('H2226', '', '', '', NULL, '', '998e17c3782d1e27598c7c15f27374af', '20190608053650', '0', '20190608053650')

One or both of these probably did us in.

Links: https://tendril.wikimedia.org/report/slow_queries_checksum?checksum=e75aa74cb532e53483222e47ba181943&host=db1075&user=wikiuser&schema=zhwikiversity&hours=168 and https://tendril.wikimedia.org/report/slow_queries_checksum?checksum=e6f5adc6ba51bede5307e608b723f201&host=db1075&user=wikiuser&schema=zhwikiversity&hours=168

Linkigg the ones from later in the day too, they probably line up with the retries: https://tendril.wikimedia.org/report/slow_queries_checksum?checksum=6b7e787ed016b255ff8fa9091fd29ddd&host=db1075&user=wikiuser&schema=zhwikiversity&hours=168

So this is likely something in MediaWiki getting hung up.

I'll merge this into the other ticket.